Field of Invention
The present invention relates to permanent magnetic devices, and more particularly to a method and an equipment for hydrogen-pulverizing NdFeB rare earth permanent magnetic alloy.
Description of Related Arts
The NdFeB rare earth permanent magnetic material is increasingly applied because of excellent magnetism, and widely applied in fields of medical nuclear magnetic resonance imaging, computer hard disk drives, audio equipments and mobile phones. Along with requirements of an energy-saving and low-carbon economy, the NdFeB rare earth permanent magnetic material is further applied in fields of auto parts, household appliances, energy-saving control electric motors, hybrid power vehicles and wind power generation.
In 1982, Japan Sumitomo Special Metals Co., Ltd. initially disclosed Japanese patent applications, JP 1,622,492 and JP 2,137,496, of the NdFeB rare earth permanent magnetic material and then submitted United States patent applications and European patent applications, wherein features, constituents and a preparation method of the NdFeB rare earth permanent magnetic material were disclosed; a Nd2Fe14B phase was confirmed as a main phase; and a rich Nd phase, a rich B phase and rare earth oxide impurities were confirmed as a grain boundary phase.
On Apr. 1, 2007, Japan Hitachi Metals Co., Ltd. merged with the Japan Sumitomo Special Metals Co., Ltd. and inherited rights and obligations of the patents of NdFeB rare earth permanent magnets of the Japan Sumitomo Special Metals Co., Ltd. On Aug. 17, 2012, the Japan Hitachi Metals Co., Ltd filed a lawsuit in United States International Trade Commission (ITC) for owning patents of U.S. Pat. No. 6,461,565, U.S. Pat. No. 6,491,765, U.S. Pat. No. 6,537,385 and U.S. Pat. No. 6,527,874 which were applied in United States.
The Chinese patent application publication, ZL93115008.6, disclosed a preparation method of a high-performance R—Fe—B permanent magnetic material, comprising steps of: smelting by a strip billet continuous casting method to obtain alloy flakes, having a main phase of a R2Fe14B phase, a thickness of 0.03-10 mm and a length less than 50 mm; loading the alloy flakes into a container for absorbing hydrogen at a pressure between 200 Torr and 50 Kg/cm2; after absorbing the hydrogen, heating at a temperature of 100-750° C. for more than 0.5 hour for dehydrogenating; powdering the alloy flakes into fine powder, having particles of an averaged size of 1-10 μm, within a inert gas jet mill; loading the fine powder into a mold and instantaneously exerting a pulse magnetic field higher than 10 KOe for an alignment; then mold-pressing, sintering and aging.
The Chinese patent publication, CN1191903C, disclosed a device for hydrogenating rare earth alloy and a method thereof, wherein the device comprises a housing, a gas inlet, a gas outlet, an airflow generating device and a wind shield. The device belongs to a single chamber hydrogen pulverization device with a low production and a high energy cost.